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05-05-2014, 02:51 PM   #1
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Asahi Pentax extension tubes

I ordered a set off of Evilbay.

Any tips on how to use them would be appreciated.

I have 3 lens. The 18-55 kit lens, the 55-300 lens, and the manual Asahi Pentax Macro F4 100mm lens.
I intend to just use them on the macro lens. But if they can be used on the other 2 I'm open to trying it to see what they will do.

05-05-2014, 02:54 PM   #2
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QuoteOriginally posted by Michael Piziak Quote
I ordered a set off of Evilbay.

Any tips on how to use them would be appreciated.

I have 3 lens. The 18-55 kit lens, the 55-300 lens, and the manual Asahi Pentax Macro F4 100mm lens.
I intend to just use them on the macro lens. But if they can be used on the other 2 I'm open to trying it to see what they will do.
You can't use them with your zooms since they lack an aperture ring, but the 100mm is a good fit. If you want to get even closer to your subjects, I'd recommend picking up a 1:1 macro lens such as the A 50mm F2.8 later on. I'm sure you'll have a lot of fun with macro photography

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05-05-2014, 03:02 PM   #3
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QuoteOriginally posted by Adam Quote
You can't use them with your zooms since they lack an aperture ring, but the 100mm is a good fit. If you want to get even closer to your subjects, I'd recommend picking up a 1:1 macro lens such as the A 50mm F2.8 later on. I'm sure you'll have a lot of fun with macro photography
Ok so the kit lens and the 55-300 is out of the question with these extension tubes.

I've taken a lot of pics with my macro lens and I enjoy it a lot. Let me ask 2 questions:

1) Do the extension tubes have connections in them so I can continue to use my green button for stop down metering ?

2) What magnification is my 100mm macro lens, 1:2 ?
05-05-2014, 03:15 PM   #4
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QuoteOriginally posted by Michael Piziak Quote
Ok so the kit lens and the 55-300 is out of the question with these extension tubes.

I've taken a lot of pics with my macro lens and I enjoy it a lot. Let me ask 2 questions:

1) Do the extension tubes have connections in them so I can continue to use my green button for stop down metering ?

2) What magnification is my 100mm macro lens, 1:2 ?
1. The issues using green button with extension tubes are the same as using green button with lenses ie is there an electrical connection with the contacts or is it painted/anodised (or does the tube have a narrow base and so not cover the contacts)? Does your camera green button work if no connection?

2. I think the M 100mm is 1: 2 - check the specs in the lens reviews.

Google using extension tubes theres lots of good info.

05-05-2014, 03:26 PM   #5
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Genuine Pentax (K-mount) tubes come in two types: what are called "auto", and fully manual. The "auto" tubes have a mechanical linkage for the diaphragm actuator, so that the lens diaphragm remains wide open until exposure. Green Button should work normally, as with the macro lens alone. The manual tubes are just spacers and the lens remains stopped down to the setting on the aperture ring. The image in the viewfinder will be rather dark if the lens is stopped down much. Again, Green Button should set the exposure properly. For that matter you can shoot in Av mode with a manual tube.

The M and K series 100/4 macro lenses are indeed 1:2. You need 50mm of extension to get to 1:1.
05-05-2014, 03:31 PM   #6
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QuoteOriginally posted by marcusBMG Quote
1. The issues using green button with extension tubes are the same as using green button with lenses ie is there an electrical connection with the contacts or is it painted/anodised (or does the tube have a narrow base and so not cover the contacts)? Does your camera green button work if no connection?

2. I think the M 100mm is 1: 2 - check the specs in the lens reviews.

Google using extension tubes theres lots of good info.
I tested it and the green button does nothing with a lens not connected.

So I assume I will just need to set my cameras shutter speed manually.

---------- Post added 05-05-14 at 03:45 PM ----------

QuoteOriginally posted by baro-nite Quote
Genuine Pentax (K-mount) tubes come in two types: what are called "auto", and fully manual. The "auto" tubes have a mechanical linkage for the diaphragm actuator, so that the lens diaphragm remains wide open until exposure. Green Button should work normally, as with the macro lens alone. The manual tubes are just spacers and the lens remains stopped down to the setting on the aperture ring. The image in the viewfinder will be rather dark if the lens is stopped down much. Again, Green Button should set the exposure properly. For that matter you can shoot in Av mode with a manual tube.

The M and K series 100/4 macro lenses are indeed 1:2. You need 50mm of extension to get to 1:1.
I believe I have the "Auto" ones on the way: Pentax Auto Extension Tube Set w 1 2 3 079 | eBay

Still, I can only use this extension tube with my Macro lens, right?
05-05-2014, 04:08 PM   #7
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QuoteOriginally posted by Michael Piziak Quote
I believe I have the "Auto" ones on the way: Pentax Auto Extension Tube Set w 1 2 3 079 | eBay
With these tubes will be exactly the same as using pentax K or M series lens alone.
05-05-2014, 04:37 PM   #8
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QuoteOriginally posted by Michael Piziak Quote
Still, I can only use this extension tube with my Macro lens, right?
That's right, only with a lens that has an aperture ring.

05-05-2014, 04:57 PM   #9
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What is the mm (individual and total) on these extension tubes?
05-05-2014, 05:02 PM   #10
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PENTAX Auto Extension Tube Set K reviews - Pentax Camera Accessory Review Database
05-05-2014, 05:15 PM   #11
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One thing is for sure, Pentax needs to make a more affordable set of these.
$550 for new ones is crazy, and the used ones are hard to come by.
http://www.amazon.com/PENTAX-auto-extension-ring-30535/dp/B000FHU7GU/ref=sr_...xtension+tubes

---------- Post added 05-05-14 at 05:19 PM ----------

Thanks baro-nite.
So 57 mm of tube will bring my f4 macro 100mm in a little better than 1:1 macro ratio
05-05-2014, 05:32 PM   #12
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QuoteOriginally posted by Michael Piziak Quote
I tested it and the green button does nothing with a lens not connected.

So I assume I will just need to set my cameras shutter speed manually.[COLOR="Silver"]

---------- Post added 05-05-14 at 03:45 PM ----------
The green button should work when these tubes are attached. The green button only activates on some bodies when the electrical contacts on the mount are shorted. The K10D and K20D I know for certain do not need a lens attached for the green button to work.

As noted above the "auto" tubes should allow you to use a lens with an aperture ring as if it were a M or K series lens. The auto tube should short the contacts as the mount is bare metal.
05-05-2014, 06:29 PM   #13
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The green button will work fine with those tubes. I have the Vivitar Auto set, but had to scrap off the black paint on them to ground the contacts so I can use catch in focus. I don't use the green button, as I've found you really need a flash for macro work, especially when working close distances. I use the X setting at 1/180 and set the aperture according to the flash setting distance, which will be right on top of your subject when using 50mm tubes on that 100mm macro.
05-06-2014, 09:59 AM   #14
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QuoteOriginally posted by bluestringer Quote
The green button will work fine with those tubes. I have the Vivitar Auto set, but had to scrap off the black paint on them to ground the contacts so I can use catch in focus. I don't use the green button, as I've found you really need a flash for macro work, especially when working close distances. I use the X setting at 1/180 and set the aperture according to the flash setting distance, which will be right on top of your subject when using 50mm tubes on that 100mm macro.
I seen an inexpensive cloth tube that goes from the flash to the front of the macro lens on Evilbay for just a few dollars.
Looking for it again now.
05-06-2014, 10:32 AM   #15
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The onboard flash will work fine, but it needs to be diffused someway. I have used a sheet of tracing paper to diffuse it. I'm now using an old Sunpak ring flash I got for cheap from KEH. It works great. There are a lot of cheap LED type ring flashes on ebay that may work ok. The Pentax AF280T shoe mount flash will also work as it will tilt down 15 degrees, and you can get a stofen diffuser for it.
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